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Iron vs steel

Iron VS Steel

Iron VS Steel: What is the Difference?

Iron and steel are the most common metals in the construction, transport and commercial industries. The applications of the two metals are so similar that most people use their names interchangeably. Despite the striking similarities in applications, steel and iron are two different metals with unique compositions in their own right.

What is Iron?

Iron is the fourth most abundant element that makes up the Earth’s inner and outer core. It is the purest metallic on the planet and is commonly used in the manufacturing of other metals. Iron, in real sense, is not the strong metal that is often used to support buildings and bridges. The iron used in construction and other applications is not pure iron but rather an alloy that is combined with other elements to achieve the physical properties it is now known for.

Physical Properties of Iron

Pure iron is silvery-white, easy to work with and you can cut through using a knife. Pure iron can be hammered into sheets and drawn into wires. Despite these surprising properties, iron still conducts heat and electricity like other metals and can be magnetised.

Chemical Properties

Pure iron will readily combine with oxygen in the air, which makes it hard to find pure iron. Even when it is combined with an alloying element, like the type used in construction, iron still reacts with moist air, forming a reddish-brown oxide (rust). The metal can react with carbon, sulphur and silicon as well.

Types of Iron

As noted earlier, pure iron is very soft and reactive. As such, it can’t be put to much use in its pure form. The material we fondly refer to as "iron" is in fact alloys of iron. The metal is mixed with other elements, mainly carbon, to increase its strength and resilience. Some of the common types of iron include:

  • Pig iron – This is basic raw iron that is moulded into blocks known as pigs.

  • Cast iron – Cast iron has very high carbon content. It is iron that has been melted then poured into a mould then allowed to cool and harden. The final product is often a structural shape.

  • Wrought Iron – This type of iron has a lower carbon content and is often made from mixing iron with slag (leftover waste). It is softer than cast iron, allowing you to change its shape by heating the metal.

What is Steel?

Steel is a type of iron alloy. It has a lower carbon content than cast and wrought iron, and it features other alloying elements to give it its properties. Like iron, there are different types of steel, but all of them contain iron.

  • Carbon steel – This is a basic type of steel that contains about 1% of carbon. Carbon steel is the most common type of steel making up 80% of the majority of steel produced each day.

  • Alloy steels – These contain iron, carbon and one or more additional alloying elements like nickel, silicon, chromium, copper, or vanadium. The properties of the emerging alloy steel depend on the type of alloying element used. One type of alloy steel is stainless steel. thyssenkrupp Materials UK is a leading stockholder of stainless steel alloys: Browse our stock range.

Differences Between Iron and Steel

Although both metals start with the same base compound, after production, they each transform into unique metals. As such, they often exhibit differences, which inform the applications each of the metals can be used for.


steel durability

Durability is a crucial factor when building structures that will stand against the elements and the test of time. Both iron and steel are quite durable. However, iron's tendency to react with oxygen and moisture makes it susceptible to corrosion.

Steel offers better durability. It can withstand immense force, heat and elements of weather, not to mention it is not affected by mould or mildew, unlike iron.

Steel does not crack, warp, twist, rot or split and is considered one of the most durable metals in construction thanks to its versatility.


anti corrosion steel coating

Corrosion is caused by chemical oxidation. Other than the layer it forms on the metal, it also alters the chemical composition of the metal.

Iron is susceptible to oxidation, leading to rust and corrosion. Steel can also be affected by water. However, there are measures that can increase resistance and reduce risk such as the use of protective paints and sprays. Besides, steel is a non-porous alloy, which means it naturally resists corrosion.


Steel is incredibly versatile. It allows for creativity and flexibility. It can be shaped and bent to the needs of any project, which is why it's commonly used to make complex forms. What stands out most about the versatility of steel is its ability to be bent and shaped without compromising its functionality. thyssenkrupp Materials UK is a leading supplier of high quality mild steel, allowing top performance no matter the application.

The versatility of iron increases when it is mixed with carbon or any other alloy. In the past, architects would use iron to fill intricate moulds. However, times have changed, and while iron can still make impressive ornate details, it's not as versatile as steel when it comes to construction.


recycling steel

Both metals are highly sustainable. However, steel has an advantage because structural steel is 100% recyclable and it can be recycled multiple times, without losing durability or strength. Steel is also considered a better option because of its durability, reducing its impact on the environment over time.

Iron is also fully recyclable. However, the recycling process is energy-intensive, which makes it less sustainable because of the carbon footprint associated.


steel costs

The cost of producing steel has dropped significantly since the industrial revolution, resulting in increased steel production because of its affordability.

Structurally, steel is lighter than iron, which gives steel a substantial advantage in the construction industry, in terms of building costs and weight of the structure. In most cases and parameters, using steel is going to be cheaper and more effective than using iron.


Both metals are used in very similar applications, including the construction of roads, railways, buildings, cooking utensils, and appliances. However, the application of each depends on its properties and durability.

Understanding these differences is critical in helping you choose the right metal for your project. If you would like some professional insight, we have in-house engineers who can help you review our extensive range of steel products.  

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